The cutoff frequency is set high in order to prevent suppression of low-frequency
components so that high-quality reception control of a radio signal can be realized.
A radio signal amplifier unit amplifies a received radio signal and results in
an amplified signal. A frequency conversion unit mixes the amplified signal with
a local oscillation signal to thereby convert the radio signal having a radio frequency
signal into the radio signal having an intermediate frequency signal, resulting
in an intermediate frequency signal. A frequency shift control unit shifts the
intermediate frequency signal towards the upper part of the frequency band. A frequency
inversion unit inverts a low-frequency side of the intermediate frequency signal
towards the upper part of the frequency band and inverts a high-frequency side
thereof towards a lower part thereof. An AC coupling unit is provided at an output
side of the frequency control unit. A radio signal demodulating unit demodulates
an output signal obtained via the AC coupling means.